1. Field of the Invention
The present invention relates to a switch used for an operation panel of en electronic device such as a portable telephone etc., for example, a click plate used for the switch and a method of attaching the click plate to a substrate.
2. Description of the Related Art
An electronic device having an operation switch, for example, a portable telephone has been spread widely and the production thereof has been increased. Thus, the company for manufacturing portable telephones is required to cope with the variety of the needs of the market such as the addition of new functions increased in accordance with the spread thereof and to reduce the manufacturing cost thereof required in accordance with the increase of the production thereof. Accordingly, it becomes difficult for the portable telephone manufacturing company to manufacture all parts of the portable telephones and to assemble the parts, so that the portable telephone manufacturing company purchases various kinds of the parts from the parts manufacturing company and assembles the parts. On the other hand, cost of the parts can not be reduced when the parts manufacturing company provides the portable telephone manufacturing company with parts of different design specification at every type of the portable telephone. Thus, normally, the design specification is standardized so as to cope with various type of the portable telephones and the parts of the same design specification are provided.
Conventionally, the configuration shown in FIGS. 1 and 2 is employed as a switch such as ten keys, function keys etc. employed for an operation panel of a portable telephone.
FIG. 1 is a perspective view showing a state where a conventional switch is assembled on a substrate which is housed within the casing of a portable telephone. FIG. 2A is a sectional view showing a state where the switch is not operated and FIG. 2B is a sectional view showing a state where the switch is operated.
In the figures, a reference numeral 1 depicts a substrate which is housed within the casing of the portable telephone and on which the wiring is printed. The main circuit section of the portable telephone such as a control section, a radio section etc. (not shown) is provided and various kinds of electronic parts are mounted on the rear surface of the substrate. A reference numeral 2 depicts electronic parts such as LEDs, resistors etc. mounted on the substrate 1, 3 a liquid crystal display element for displaying a telephone number and a menu screen, 4 a speaker, 5 a microphone, 6 and 7 first and second contact patterns formed on the substrate 1 with a predetermined distance therebetween concentrically, and 8 an outer chassis which is formed by molding resin and constitutes a part of the casing of the portable telephone. A reference numeral 9 depicts a click plate which is made from electric conductive material and includes a peripheral portion 10 and a convex portion 11 which center portion is expanded and made hollow. The peripheral portion 10 is coupled to the contact pattern 6 and the convex portion 11 is arranged in a manner that the inner surface of its hollow portion can be coupled to the contact pattern 7 when it is pushed and deformed. A reference numeral 12 depicts an adhesive sheet adhered to the click plates in a state that the click plates 9 are respectively disposed at predetermined positions in advance. The arrangement of the click plates 9 is made correspond to the arrangement of the contact patterns 6 in a manner that the peripheral portions 10 of the click plates 9 are coupled to the corresponding contact patterns 6 respectively when the adhesive sheet is pasted on the substrate 1. A reference numeral 13 depicts a hole provided at the adhesive sheet 12 so as to correspond to the position of the associated electronic part 2 when the adhesive sheet 12 is pasted on the substrate 1. A reference numeral 14 depicts a key switch which is formed by silicon rubber and includes a key top portion 15 and an actuator portion 16.
The manufacturing procedure of the conventional switch thus configured will be explained with reference to FIG. 1.
That is, the adhesive sheet 12 to which the click plates 9 are pasted is fabricated by the parts manufacturing company. The click plates 9 are pasted on the adhesive surface of the adhesive sheet 12 in the arrangement determined by the standard specification. The adhesive surface of the adhesive sheet 12 is pasted on the substrate 1 so that the peripheral portions 10 of the click plates 9 are disposed on the corresponding first contact patterns 6 respectively. In this case, the convex portions 11 of the click plates 9 are positioned at the portions corresponding to the associated second contact patterns 7, respectively. Further, the electronic parts 2 on the substrate 1 fit into the corresponding holes 13 of the adhesive sheet 12 so as to be positioned at portions not covered by the adhesive sheet 12.
The electronic parts 2 are attached to the substrate 1 normally in a manner that the electronic parts are mounted on the substrate by using a mounting machine and then soldered by the reflow soldering process. The electronic parts are attached on the substrate in the following procedures. First, a metal plate calling a metal mask is superimposed on the substrate 1 to mask the substrate, and the cream solder is pasted. The metal mask is provided with holes at the portions corresponding to pad portions on the substrate 1 to which the electronic parts are attached. Thus, when the substrate 1 is masked and the cream solder is pasted, the cream solder is pasted only on the pad portions. Then, the terminal portions of the electronic parts 6 are positioned on the pad portions on which the cream solder is pasted and then mounted on the pad portions. The mounting procedure of the electronic parts 2 on the substrate 1 is performed in a manner that, for example, a computer reads the soldering portions of the electronic parts 2 and the electronic parts are mounted on the substrate by using a mounting machine. Then, the substrate 1 on which the electronic parts 6 are mounted is subjected to the reflow process to apply predetermined heat on the substrate 1 to melt the cream solder, whereby the terminal portions of the electronic parts 2 are soldered on the corresponding pads, respectively.
Further, at the time of assembling a portable telephone, as shown in FIG. 2A, the key switch 14 is disposed in a manner that the tip portion of the actuator 16 is positioned almost at the center portion of the convex portion 11 of the corresponding click plate 9 and the key switch 14 is held such that it is sandwiched between the substrate 1 and the outer chassis 8.
The liquid crystal display element 3, the speaker 4 and the microphone 5 are coupled to and mounted on the substrate 1 by solder and connectors. In recent years, due to the improvement of the part mounting technique and the part manufacturing technique, these parts are made cope with the mounting machine and the automatic mounting technique employing the reflow process so long as the parts are not such ones as the liquid crystal display element 3 which is largely influenced by the breakage caused by the heat at the time of the reflow process.
Then, the operation of the switch will be explained with reference to FIGS. 2A and 2B.
When a user of the portable telephone pushes the key top portion 15 as the key operation, the actuator 16 pushes and deforms almost the center portion of the convex portion 11 of the corresponding click plate 2 in an interlocked manner with the key top portion 15 as shown in FIG. 2B, so that the inner surface of the hollow portion of the convex portion contacts with the corresponding second contact pattern 7. In this case, the first contact pattern 6 is made conductive with the corresponding second contact pattern 7 through the corresponding click plate 9. Thus, a desired control signal is transmitted to the electronic parts 2 on the substrate 1 and so characters, signs etc. corresponding to the key operation are displayed on the liquid crystal display element 3.
Since the conventional switch is configured in the aforesaid manner, there are the following problems.
That is, the cost can not be reduced when the adhesive sheet 12 having different arrangement of the click plates 9 at every type of a portable telephone having different key arrangement and substrate plate is provided. Thus, it is required to reduce the cost by standardizing the design specification so as to cope with various types of the portable telephones and providing the adhesive sheet 12 having the common arrangement of the click plates.
However, in fact, in order to cope with the variety of the needs of the market such as the addition of new functions increased in accordance with the spread of the portable telephones, the portable telephone manufacturing company must purchase from the parts manufacturing company the adhesive sheets 12 of the respective specifications on which the click plates 9 are arranged in accordance with the respective types of the portable telephones, so that there arises a problem that the cost of the portable telephone becomes expensive.
Further, there arises a problem that the thickness of the switch becomes thicker by the thickness of the adhesive sheet 12. As a result, the thickness of the portable telephone is influenced by the thickness of the adhesive sheet. That is, in recent years, the miniaturization of the portable telephone is progressively advanced by miniaturizing and light-weighting the respective electronic parts 2, the outer chassis 8 etc. in accordance with the needs of the market. Since, usually, the entire thickness of the portable telephone is almost occupied by the thickness of a battery disposed at the rear surface side of the portable telephone, it is most effective to make the thickness of the battery thinner in order to make the portable telephone thinner. However, the thickness of the battery is depending on the technique of the battery manufacturing company. Further, due to the increase of the call waiting time of the telephone in accordance with the needs of the market, the electric capacity of the battery has been increased, and so the miniaturization of the battery can not so be expected to such a degree of the actual technical development. Thus, the portable telephone manufacturing company has developed so as to make the thickness of the various kinds of parts other than the battery such as the substrate 1, the electronic parts 2, the outer chassis 8 etc. to their limited values.